A “popcorn-making-mimic” strategy for compounding graphene@NiFe2O4 flexible films for exceptionally strong electromagnetic interference shielding and absorption

Abstract

Compounding functional nanoparticles with highly conductive and porous carbon scaffolds is a basic pathway for engineering many important functional devices. However, enabling uniform spatial distribution of functional particles within a massively conjugated, monolithic and mesoporous structure remains challenging, as the high processing temperature for graphitization can seriously arouse nanoparticle ripening, agglomerations and compositional changes. Herein, we report a unique “popcorn-making-mimic” strategy for preparing a highly conjugated and uniformly compounded graphene@NiFe2O4 composite film through a laser-assisted instantaneous compounding method in ambient condition. It can successfully inhibit the unwanted structural disintegration and mass loss during the laser treatment by avoiding oxidation, bursting, and inhomogeneous heat accumulations, thus achieving a highly integrated composite structure with superior electrical conductivity and high saturated magnetization. Such a single-sided film exhibits an absolute shielding effectiveness of up to 20906 dB cm2 g-1 with 75% absorption rate, superior mechanical flexibility and excellent temperature/humidity aging reliability. The electromagnetic interference shielding effectiveness can reach 51 dB for a double-sided film with the thickness of 166 µm, which shields approximately 99.999% of the incident electromagnetic waves. These performance indexes signify a substantial advance in EMI absorption capability, fabrication universality, small form-factor and device reliability toward commercial applications. Our method provides an important paradigm for fabricating sophisticated composite materials for versatile applications.